JPS6027865B2 - piston pin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston pin, particularly a piston pin for an internal combustion engine, and more particularly, the present invention relates to a piston pin for an internal combustion engine. A recess is provided in all or part of the outer circumferential surface of the piston pin up to the inner end edge region, and this recess relates to a piston pin having a conical taper in the axial direction.

A piston pin is a power transmission member that connects a piston and a connecting rod.

The piston pin deflects or deforms into an oval shape due to the force applied to it. As the piston periodically deforms, ie flexes and flattens, the boss of the piston is subjected to loads both in the horizontal and vertical planes. If the piston pin itself is of suitable dimensions in terms of strength, the average load experienced by the boss to support the pin will generally be within acceptable limits, taking into account the often inadequate lubrication. In case of aluminum, the weight should be within 600 kg/.
However, even if this is satisfied, the load near the inside and upper part of the pin bearing boss will be many times the above average value due to the deflection of the pin. In unfavorable cases, this results in a so-called cracking skin (h) on the boss. Particularly when starting an engine, very high peak pressures generally occur;
This, combined with the narrow clearance between the pin and the boss, can result in unacceptably high stresses in the boss due to the oblong deformation of the pin. Extensive research has shown that, inter alia, in the case of diesel engine pistons, the location of the highest stress in the piston is found near the inner upper edge of the pin hole. As a method to reduce the peak stress in this region, for example, benzine gel. Double. Day. And hey. “Pistons, piston rods and crankshafts in high-speed internal combustion engines” by Maya,
Berlin/Götztingen/Heidelberg, 1961 edition, p. 10, states that near the inner edge of the pin bearing boss, its corners may be rounded to radius 1, or the boss may be rounded without causing excessive stress in the piston member. It is stated that elasticity is provided in the region of the boss to accommodate the deflection of the piston pin.

It has also been proposed to form the inner edge of the post into a taper with a slope of 1:low. In this connection, it is known from DE 12 09 844 A1 to provide a rectangular reinforcing ring around the outer periphery of the hub and to secure it by shrinkage.

This part of the boss is fixed by shrinkage with a reinforcing ring.
In operating conditions, this causes a slight expansion compared to the rest of the post, so the hole in the boss narrows towards the side of the ring and is fixed by contraction to compensate for this difference in expansion.
As a result, in the operating state, the hole is again the same cylindrical shape as without the reinforcing ring. German Patent Application Publication No. 1, 6
No. 50,206 already discloses that the hole of the pin bearing boss is formed in an oval shape, the minor axis radius of which extends parallel to the longitudinal axis of the piston, thereby allowing play between the boss and the pin. At the same time as making it as small as possible, it also increases competition resistance.
It also describes a method that reduces noise.

Another type of boss hole of this kind is known from German Patent Application No. 2,152,426 in which the boss hole has a shape corresponding to the mechanical and thermal loads applied by the piston pin. be.

Such a special shape for the piston boss hole necessarily results in high manufacturing costs, so it is still practical to form the edge of the boss hole into a circular shape, even if this does not minimize the load on the boss. That's advantageous. The object according to the invention is that at maximum load, the peak of the post (Schei
), particularly at the inner upper edge, is uniformly distributed over the entire length of the pin in the boss hole and engaged with the boss.

The above purpose is to extend all or part of the outer circumferential surface of the piston pin from each inner edge area of both posts of the piston supporting the piston pin to the inner edge area of the 4/end bearing of the connecting rod. A recess is provided in the piston pin, and the recess has a conical taper in the mar direction, and the depth of the recess at a predetermined position is at least equivalent to the deflection of the pin due to a design load at the same predetermined position. This is achieved by In order to ensure that the piston pin never loads on the edges, the depth of the recess is preferably only slightly deeper than the value of the local deflection of the piston pin.

This recess is preferably formed into a conical taper with an inclination angle of 8 to 14.

In this way, the stresses occurring in the piston post and the stove are kept within permissible limits, so that there is no risk of green pressure and therefore cracks in the boss.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

- A piston pin 4 is inserted into the hole 1 of the boss 2 of the piston 3, and this pin 4 has an inner end green area extending from each inner edge area of the boss 2 to the inner end green area of the small end bearing 5 of the connecting rod. A recess 6 is formed on the outer peripheral surface of the
This recess 6 has a conical taper in the direction opposite the pin 4.

The depth of this recess 6 is formed to be slightly deeper than the local deflection of the pin 4 due to the design load.

[Brief explanation of the drawing]

The drawing is a partially sectional side view of a piston pin according to an embodiment of the present invention. In the symbols used in the drawings, 1 is a hole, 4 is a piston pin, and 6 is a recess.

Claims (1)

[Scope of Claims] 1. From the respective inner edge regions of both bosses 2 of the piston 3 supporting the piston pin 4 to the inner edge region of the small end bearing 5 of the connecting rod, the piston pin 4 therebetween. A recess 6 is provided in all or part of the outer circumferential surface of the piston pin, and the recess 6 has a conical taper in the axial direction. A piston pin characterized in that it is configured to correspond to the deflection of pin 4. 2. The piston pin according to claim 1, wherein the concave portion 6 has a taper of 8 to 14 degrees.